1. Field of the Invention
The present invention relates to a projection television apparatus.
2. Description of Related Art
A projection television apparatus is available, which includes a frame, a rear projection screen attached to a front surface of the frame, and a projector unit, disposed in the frame, for emitting an image projection light beam onto a rear surface of the rear projection screen via a projection lens.
The projector unit is provided with image forming means including, e.g., transmissive liquid crystal display units, whereby light beams emitted from a light source are modulated by the liquid crystal display units on the basis of image information to generate the image projection light beam.
FIG. 22 is a front view of such a projection television apparatus 1. In a front surface 4 of a frame 2 is a rectangular screen 6, which is disposed with its long sides aligned with the horizontal direction and its short sides with the vertical direction.
In such a projection television apparatus, due to the projector unit being out of position with respect to the frame, specifically, due to the liquid crystal display units being out of position in a direction of rotation around the corresponding optical axes of the light beams passing through the liquid crystal display units, four sides of an image G projected onto the screen 2 do not parallel four sides of the screen 6 as shown by a broken line, and thus the image G suffers deviations from the screen 2 in the direction of rotation.
In order to overcome this inconvenience, an adjusting technique has been proposed (see Patent Document 1), in which an adjusting mechanism having a fixed table secured to the frame 2 and a rotating table rotatably supported by this fixed table is provided. The projector unit is attached to the rotating table, and the rotating table is then rotated around an optical axis of the projection lens for adjustment.
According to such a conventional technique, by rotating the entire projector unit together with the rotating table, the deviations in the rotational direction suffered by the image G can be eliminated.
[Patent Document 1] Japanese Patent Application Publication No. 2000-10188
However, in this conventional technique, the entire projector unit is rotated together with the rotating table, for which a large-scale adjusting mechanism and hence a large space are required. Thus, the conventional mechanism is disadvantageous in reducing not only the size and thickness of the projection television apparatus but also its cost.